In recent years, as display monitors for liquid crystal televisions, notebook personal computers and car navigation systems, liquid crystal displays (LCDs) are frequently used. The liquid crystal displays are classified into various display modes (systems) depending on molecular arrangement (alignment) of liquid crystal molecules included in a liquid crystal layer sandwiched between substrates. As a display mode, for example, a TN (Twisted Nematic) mode in which liquid crystal molecules are twisted to be aligned in a state where no voltage is applied is well known. In the TN mode, liquid crystal molecules have positive dielectric anisotropy, that is, a property in which the dielectric constants in a long-axis direction of the liquid crystal molecules are larger than those in a short-axis direction. Therefore, the liquid crystal molecules are configured to be aligned in a direction perpendicular to a substrate surface in a plane parallel to the substrate surface while sequentially turning the alignment directions of the liquid crystal molecules.
On the other hand, a VA (Vertical Alignment) mode in which liquid crystal molecules are aligned perpendicularly with respect to a substrate surface in a state where no voltage is applied attracts increasing attention. In the VA mode, liquid crystal molecules have negative dielectric anisotropy, that is, a property in which dielectric constants in a long-axis direction of liquid crystal molecules are smaller than those in a short-axis direction, and a wider viewing angle than that in the TN mode is achievable.
Such a VA mode liquid crystal display has a configuration in which when a voltage is applied, liquid crystal molecules aligned in a direction perpendicular to a substrate are turned in a direction parallel to the substrate in response to the application of the voltage by negative dielectric anisotropy, thereby allowing light to pass therethrough. However, as the liquid crystal molecules aligned in the direction perpendicular to the substrate are turned in an arbitrary direction, the liquid crystal molecules are misaligned by the application of the voltage to cause deterioration of response characteristics with respect to voltage.
Therefore, to improve response characteristics, a technique of limiting a direction where liquid crystal molecules are turned in response to a voltage has been studied. More specifically, a technique (photo-alignment film technique) of providing a pretilt angle to liquid crystal molecules with use of an alignment film formed by applying linearly-polarized light of ultraviolet light, or applying ultraviolet light in an oblique direction with respect to a substrate surface, and the like have been studied. As the photo-alignment film technique, for example, there is known a technique of forming an alignment film by applying linearly-polarized light of ultraviolet light or applying ultraviolet light in an oblique direction with respect to a substrate surface to a film made of a polymer including a chalcone structure to cross-link a double bond portion in the chalcone structure (refer to PTLs 1 to 3). Moreover, in addition to this, there is a technique of forming an alignment film with use of a mixture of a vinyl cinnamate derivative polymer and a polyimide (refer to PTL 4). Further, a technique of forming an alignment film by applying linearly-polarized light with a wavelength of 254 nm to a film including a polyimide to decompose a part of the polyimide (refer to PTL 5), or the like is known. Moreover, as a technique related to the photo-alignment film technique, there is a technique of forming a liquid crystal alignment film by forming a film made of a liquid crystal polymer compound on a film made of a polymer including a dichromatic photoreactive building block such as an azobenzene derivative irradiated with linearly-polarized light or oblique light (refer to PTL 6).